In a food processor, add butter, half the rice flour and the brown sugar. Pulse until mixture resembles coarse cornmeal. Add remaining rice flour, vanilla, cornstarch, salt, milk and egg yolk. Process until dough comes together in a ball. Remove dough and press evenly into an ungreased 9-inch-square baking pan. Prick several times with fork. Bake about 20 minutes or until golden. Remove and let cool in pan on a wire rack.

Filling -

In a medium nonstick saucepan, combine butter, sugar and condensed milk and cook over medium-low heat until the mixture comes to a boil. Reduce heat and cook 5-10 minutes until the caramel is pale golden, thick and is coming away from the sides of the pan. Quickly pour the topping over the cookie base in the pan and let cool. When you can touch the top and it is no longer sticky, place the pan in the refrigerator to cool completely.

Chocolate Covering

In a 1 or 2 cup glass pyrex measuring cup, melt the chocolate for 30 seconds on medium power. Stir chips. If needed, microwave again in 15 second intervals, stirring after each interval, until chocolate is completely melted.

Remove the baking pan from refrigerator and cut the cookies into finger-size shapes. I cut it in half first, then cut each half into about 10 long rectangles. Place cookies on a parchment-lined baking sheet. Pour chocolate over each cookie until all are covered. Place in the refrigerator for a few minutes to set chocolate if needed.